A document filed in court Saturday by the Department of Justice said al Libi died after his already poor health suddenly worsened.

On Wednesday, the letter filed with the judge presiding over the trial said, he "was taken from the Metropolitan Correctional Center to a New York hospital due to sudden complications arising out of his long-standing medical problems."

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Despite the care provided at the hospital, it said, his condition deteriorated rapidly and he passed away Friday evening.

"We understand that, in addition to his counsel, an Imam was with (al Libi) at the hospital and that appropriate arrangements are being made with his family," the letter said.

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Al Libi arrives in the U.S.

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Al Libi arrives in the U.S. 02:08

Al Libi was indicted in 2001 by the federal court in the Southern District of New York on charges of conspiracy to kill U.S. nationals, murder, destruction of American buildings and government property and destruction of national defense utilities of the United States.

More than a decade later, the top U.S. terror suspect was captured on the street in front of his home as he returned in his car from morning prayers.

He was then held on a U.S. Navy ship for several days -- where he was questioned by members of a high-value detainee interrogation team -- before being taken to New York.

When he appeared in federal court in New York, he pleaded not guilty to terrorism charges brought against him and told the judge he played no role in the 1998 attacks.